Adobe Audition

Manipulate and adjust audio levels manually

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Watch this tutorial to learn how to adjust audio levels to reduce the volume of a section of audio with Adobe Audition.

Audition makes it really easy to adjust the amplitude - the volume of a clip that you're working with in the Waveform Display.
Let's take a look at a couple of approaches to this. Under my Assets, I've got this Millionaire Mix.mp3. I'm going to double-click to open this up. And once the MP3 has been read, you can see, this is a pretty noisy clip.
I've got my left and right channels, and down here you can see my Spectral Display. It's pretty noisy right the way across the frequency spectrum. What I'm looking for is this little panel here. This is the so-called Heads-Up Display, and this is here to allow me to make adjustments to the amplitude, to the volume, of either the whole clip or the selections that I've made.
Notice that it's got a little pin here on the right hand side. Now, if I turn that pin off, and then maybe make a selection, you can see, when I make the selection, the Heads-Up Display jumps to the middle of it. Wherever I click and drag, I get the Heads-Up Display.
Now personally, I find this a little bit intrusive, so I'm going to turn that pin on. I'm going to move the Heads-Up Display out of the way, and you'll see, now it just stays wherever I put it. With nothing selected, if I now click and drag on this decibel scale, you can see I immediately get feedback that shows the changes to the audio level in terms of adjustments to the waveform.
And now let's go for maybe -6 dB. I release the mouse button and the change is calculated and also the entire clip is selected. So I'm going to click to deselect, and you can see right away now, there's my shortened waveform. I've reduced this by 6 DB, and it's pretty subtle, but the Spectral Display has got a little bit darker. And it should do, because all of the frequencies have gotten a little bit quieter.

Now if I press Ctrl+ Z or Command+Z, just watch the Spectral Display when I do this, and then I'll deselect. You see it gets a little bit brighter. Now, if I make an individual selection, which I'll do here, and now click and drag, you'll see, it's pretty obvious what's going on. I'm just reducing the amplitude of the selection. And again, if I click away, it's much more obvious now in the Spectral Display where the darker region is. And what's beautiful about this is that it applies to selections within the Spectral Display as well. Now, I'm just going to select this clip, hit the Delete key to get rid of it from my Files panel. I get the option to save changes, I'm not going to save changes. Remember that Audition is a destructive editing system, so changes that you make are made to the file itself on your hard drive. Now, I'm going to go to this Clean up folder and open up Interview-Noise_audio.wav. Let's double click to open that up. And now I'm going to just resize a bit so you can see what's going on here, very clearly. Here's my telephone ringing in the background, that I want to get rid of in this clip. Let's have a little listen. Now, there are some wonderful noise reduction, noise cancelling effects inside of Audition, but let's say I just want to reduce the amplitude of that section of my audio. Well, I need to make a selection, I'm going to just pick up the Marquee tool here, I can now click and drag around this section of the audio. You see it's snapping to the four second mark at the top there, which is making the selection a little bit more difficult. So I'm going to turn off snapping by toggling this button at the top right hand corner of the display. And now I get a free selection. That's fine. And now if I reduce the volume- and I'm going to make this pretty obvious. You might make this a little bit more subtle, I'm going to click and drag to reduce the amplitude by quite a lot, maybe about 12 dB. And now, if I click away, again, you can clearly see the darkened region in the Spectral Display. You can do this for any piece of the audio you like. And what's beautiful about making these adjustments in the Spectral Display is that I've left alone all of the other frequencies. Everything else is clean. I've just selected that precise part that I wanted to reduce.

So this is how you can manually adjust the audio level of your clips inside Adobe Audition.

Open an audio clip in Adobe Audition and select the section of audio you want to adjust.

In the menu above the audio channel, click and drag the decibel (dB) scale to adjust the volume.

Select another part of the track and repeat step 2 to adjust the volume levels on a different section.